Rock fall at Yosemite National Park could alter popular Half Dome climb

Half Dome

Mark Boster / Los Angeles Times

A photographer walks away with his tripod over his shoulder and Half Dome in the background at Glacier Point in May 2013. A massive sheet of rock has fallen from the vertical face of Half Dome, making one of the most popular routes attempted by climbers in North America even more challenging, park officials said Tuesday.

A photographer walks away with his tripod over his shoulder and Half Dome in the background at Glacier Point in May 2013. A massive sheet of rock has fallen from the vertical face of Half Dome, making one of the most popular routes attempted by climbers in North America even more challenging, park officials said Tuesday.

While large, rock falls of this magnitude are relatively common at the park, Stock said, and occur about once a year in a process known as exfoliation. Water, ice, earthquakes and plant growth could trigger unpredictable falls.

In this case, roughly 800 cubic meters of rock was stripped from the steep sheer face of Half Dome during heavy rainstorms sometime late Thursday or early Friday, Bailey said. Park officials believe rain was the likely culprit.

He measured time — three seconds of free fall — before the baffles of his wingsuit inflated, and the resistance of his body against the air pushed back against...

Stepping off Taft Point on the evening of his death, Dean Potter tensed his body and set a trajectory through the sky above Yosemite Valley.

He measured time — three seconds of free fall — before the baffles of his wingsuit inflated, and the resistance of his body against the air pushed back against...

(Thomas Curwen)

No one witnessed the rock fall and no one was hurt, Bailey said.

The affected route, recognized in the classic climbing guide Fifty Classic Climbs Of North America, is open to rock climbers, she said.

According to the climbing guide Supertopo, the 2,000-foot-high climb has 23 pitches and takes about three days to complete.

In Supertopo’s online forum, climbers said the ledge near Robbins traverse was missing.

In 2014, there were 77 documented small rock falls, an increase from the average of 45 small rock falls per year. The largest rock fall occurred March 31 last year when 5,000 cubic meters fell from the north wall of the Hetch Hetchy Valley, burying the Rancheria Trail below.